The invention is based on a fuel supply system for furnishing fuel for an internal combustion engine and to a method for operating an internal combustion engine as defined hereinafter.
Until now, there have been fuel supply systems in which a first fuel pump pumps fuel from a fuel tank to a second fuel pump via a fuel connection. The second fuel pump in turn feeds the fuel via a pressure line to at least one fuel injection valve. Typically, the number of fuel injection valves is equal to the number of cylinders of the engine. The fuel supply system may be constructed such that the fuel injection valves inject the fuel directly into an engine combustion chamber. In operation of this fuel supply system, high pressure in the pressure line leading to the fuel injection valve is necessary.
Since during operation of the engine, a high pressure prevails in the fuel connection and even more in the pressure line leading to the fuel injection valve, problems can arise unless this high pressure is reduced after the engine is shut off. Unless this high pressure is reduced, fuel can escape to the outside, in repair situations. Unless the pressure line is pressure-relieved, the danger exists that if one of the fuel injection valves leading into the combustion chamber does not close fully, then when the engine is shut off fuel will enter a combustion chamber of the engine.